1. Field of the Invention
The present invention relates to a filling and forming method for dental viscous plastic materials such as composite resins. More particularly, it pertains to a method for dental treatments of high efficiency and high quality in a wide area of dentistry. The method involves the application of ultrasonic vibrations to the tips of filling or forming instruments. With the obtained fine vibration effect, it is possible to most effectively prevent the adhesion of the material to the instruments, which has been the gravest problem in operations, and to cause a decrease in the consistency of the material, thereby making the filling and forming of the material easy and, at the same time, improving the close adaptation of the material with respect to an application body.
2. Statement of the Prior Art
Referring typically to the tooth restoration with a composite resin, in which considerable weight is given to the aesthetical properties, filling and forming are very important steps. However, the operation for forming a resin material is troublesome, complicated, and hard to carry out. Therefore, a great deal of efforts have been devoted to simplifying this operation with enhanced efficiency. However, these efforts are limited to mere improvements in the form of the tip portions of forming instruments, and spatulashaped filling instruments are still frequently used. So far as is known by the present invention, an instrument having a vibrational function has not been used for this purpose. Although current instruments are formed of metals, plastics, etc., the resin material adheres to whatever forming instruments are used. Thus, difficulty experienced in forming still remains unsolved.
Fundamentally, the conventional methods for filling and forming dental viscous materials have several disadvantages, including:
(1) Adhesion of the material to forming instruments,
(2) Slip of the material on and along the body to which it is applied, and
(3) Deficiency in the close adaptation of the material to the body to which it is applied. However, these disadvantages have only been handled by makeshift means.
Reference will now be made to tooth restoration with a composite resin by way of example.
(1) Adhesion of Resin Material to Forming Instrument
The resin material adheres to a forming instrument which may be formed of a metal or plastics, or may be surface-treated with Teflon.RTM.. Whenever the resin material adheres to the tip of the forming instrument, it has been wiped off by a cotton ball impregnated with an alcohol so as to repeatedly use that instrument for filling. This method is far from being satisfactory, partly because it involves a very troublesome operation and partly because it is likely that such a separating agent may cause the degradation of the nature of the resin, or may decrease the close adaptation and adhesion of the resin to the cavity wall.
(2) Slip of the Placed Resin on the Cavity Wall
In recent years, much use has been made of resins containing an increased amount of fillers and, hence, showing a high degree of consistency. Such resins are convenient, since they can easily be filled and formed in intra coronal cavities such as Class I or 2 cavities. In the case of wedge-shaped defect cavities or extensive Class 5 cavities, however, the resin material tends to slip on and along the cavity wall according to the movement of the instrument, and the resin is not always easy to handle. This is because the resin material is hard and poor in flowability. As a result, forming cannot be carried out until, after filling the resin into the cavities, the consistency thereof decreases with a temperature rising to such an extent that the resin material closely adheres more or less to the surface of the cavity wall owing to a slight increase in the flowability thereof. This is the present situation, and it incurs inconvenience. Under such a condition, since the resin may still tend to slip considerably on the cavity wall, some difficulty is still encountered in forming with a manual filling instrument.
(3) Deficiency in the Close Adapation of Resin Material to the Cavity Wall
When using a resin which has a low flowability, the resin tends to slip easily on the cavity wall, and it is apt to adhere to the forming instrument, and sufficient close adaptation of the resin material to a cavity wall is not achieveable by filling under pressure relying upon the manual instrument.